An investigational 9-valent human papillomavirus vaccine could prevent up to 85 percent of invasive cervical cancer, according to a spokesman for Merck, the company developing the product. The vaccine adds five new HPV strains to the four already included in the current quadrivalent vaccine. The addition of HPV strains 31/33/45/52/58 should protect against the 30% of cervical cancers that are not caused by HPV 16 and 18, Dr Alain Luxembourg said at a meeting of the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices in Atlanta.